collision detection is a problem, i don't know how to make the counters stop in a certain place.

I am making it a simple 2 player game, so no AI is needed, also diagonal wins are not included, just basic horizontal and vertical connect4.

My main problem is actionscript is far from my strong point, I struggle to understand many functions and how to implement them. So when I say I need help, I need a lot! thanks for the post back, hopefully you can help!